The utility model provides a high temperature and high pressure suspension stability tester which comprises a heater, a control cabinet, a suction and exhaust valve, a cosy and sampling valves, wherein the heater is placed on a container, the control cabinet is connected with the heater and is used to control the heater for container heating; the suction and exhaust valve is connected inside the container and used to change pressure inside the container; the cosy is covered on the outer surface of the container; the sampling valves are placed on the container. Three sampling valves which are evenly distributed are provided. The three sampling valves are of equal disjunction distribution along the length direction of the container. The high temperature and high pressure suspension stability tester has the advantages of being strong in stability, easy to control or use, capable of simulating conditions of different temperature and pressure under a well and measuring the suspension stability of drilling fluid under the simulation conditions.